Electromigration　is　one　of　the　severe　reliability　problems　in　IC　progress.　In　this　paper,　the　electromigration　of　eutectic　Sn3.8Ag0.7Cu　Solder　reaction　couples　were　studied　under　high　temperature　(150　degrees　C)　and　high　current　density　(5　x　10(3)　A/cm(2))　in　three　days.　An　original　design　which　could　reduce　the　local　joule　heating　caused　by　current　crowding　was　produced.　Voltage　change　was　also　monitored　during　this　experiment.　Hillocks　and　valleys　were　found　at　the　anode　side　and　cathode　side　respectively.　Unlike　aging　test,　electromigration　could　promote　the　formation　of　intermetallic　compound　(IMC)　at　cathode　side　and　inhibit　the　formation　of　IMC　at　anode　side.　Cracks　also　appeared　along　the　cathode　side　after　electromigration　in　three　days,　but　they　were　not　leading　the　solder　reaction　couple　to　failure.